/*
   @Copyright:Luogu
   @Author:   tjyemail
   @Problem:  https://www.luogu.com.cn/problem/P1002
   @Language: C++
   @Datetime: 20-08-13 10:07
   */

#include <bits/stdc++.h>
using namespace std;

int main()
{
	const int H[9][2] = {{-2, -1}, {-2, 1}, {-1, -2}, {-1, 2}, {1, -2}, {1, 2}, {2, -1}, {2, 1}, {0, 0}};
	int bx, by, hx, hy;
	scanf("%d %d %d %d", &bx, &by, &hx, &hy);
	vector<vector<long long> > dp(bx+1, vector<long long>(by+1, 0));
	auto dead = [&](int x, int y)->void {
		if (x>-1 && x<dp.size() && y>-1 && y<dp[x].size()) dp[x][y] = -1;
	};
	for(int i=9; i--; dead(hx+H[i][0], hy+H[i][1]));
	dp[0][0] = 1;
	for(int x=0; x<=bx; ++x) {
		for(int y=0; y<=by; ++y) {
			if (dp[x][y]==-1) continue;
			if (x>0) dp[x][y] += dp[x-1][y]!=-1 ? dp[x-1][y] : 0;
			if (y>0) dp[x][y] += dp[x][y-1]!=-1 ? dp[x][y-1] : 0;
		}
	}
	printf("%lld\n", dp[bx][by]);
	return 0;
}
